Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, People's Republic of China.
J Exp Bot. 2013 Jan;64(1):199-213. doi: 10.1093/jxb/ers323. Epub 2012 Nov 30.
Heavy metal pollution often occurs together with organic contaminants. Brassinosteroids (BRs) induce plant tolerance to several abiotic stresses, including phenanthrene (PHE) and cadmium (Cd) stress. However, the role of BRs in PHE+Cd co-contamination-induced stress amelioration is unknown. Here, the interactive effects of PHE, Cd, and 24-epibrassinolide (EBR; a biologically active BR) were investigated in tomato plants. The application of Cd (100 µM) alone was more phytotoxic than PHE applied alone (100 µM); however, their combined application resulted in slightly improved photosynthetic activity and pigment content compared with Cd alone after a 40 d exposure. Accumulation of reactive oxygen species and membrane lipid peroxidation were induced by PHE and/or Cd; however, the differences in effect were insignificant between Cd and PHE+Cd. The foliar application of EBR (0.1 µM) to PHE- and/or Cd-stressed plants alleviated photosynthetic inhibition and oxidative stress by causing enhancement of the activity of the enzymes and related transcript levels of the antioxidant system, secondary metabolism, and the xenobiotic detoxification system. Additionally, PHE and/or Cd residues were significantly decreased in both the leaves and roots after application of EBR, more specifically in PHE+Cd-stressed plants when treated with EBR, indicating a possible improvement in detoxification of these pollutants. The findings thus suggest a potential interaction of EBR and PHE for Cd stress alleviation. These results advocate a positive role for EBR in reducing pollutant residues for food safety and also strengthening phytoremediation.
重金属污染通常与有机污染物一起发生。油菜素内酯（BRs）诱导植物耐受多种非生物胁迫，包括菲（PHE）和镉（Cd）胁迫。然而，BRs 在 PHE+Cd 共污染诱导的胁迫缓解中的作用尚不清楚。在这里，研究了番茄植物中 PHE、Cd 和 24-表油菜素内酯（EBR；一种具有生物活性的 BR）的相互作用效应。单独施用 Cd（100 µM）比单独施用 PHE（100 µM）更具植物毒性；然而，与单独施用 Cd 相比，在 40 天暴露后，它们的联合应用导致光合作用活性和色素含量略有提高。活性氧和膜脂过氧化的积累是由 PHE 和/或 Cd 引起的；然而，Cd 和 PHE+Cd 之间的影响差异不显著。叶面喷施 EBR（0.1 µM）可缓解 PHE 和/或 Cd 胁迫下植物的光合作用抑制和氧化应激，这是通过增强抗氧化系统、次生代谢物和外来化合物解毒系统的酶活性及其相关转录水平来实现的。此外，EBR 处理后，叶片和根系中的 PHE 和/或 Cd 残留量显著降低，尤其是在 EBR 处理的 PHE+Cd 胁迫植物中，表明这些污染物的解毒能力可能有所提高。因此，这些结果表明 EBR 与 PHE 之间可能存在相互作用，可缓解 Cd 胁迫。这些结果表明，EBR 在减少污染物残留以确保食品安全和加强植物修复方面具有积极作用。
